Molly sighs as she looks at her list and wonders what she has forgotten.

Easter eggs x7

Wool for scarves for the twins' birthday

Bludger for the twins' birthday (bad idea??)

New shoes for Ginny

Not a huge list, but it will stretch the budget further than she likes. And the kids will expect at least an ice cream as reward for being dragged around the shops. In an ideal world, Percy should have new school robes - his are far too short. But it is not an ideal world and he will have to wait until after the summer. Bill will have left school then, and Percy can have his old ones. She is trying not to think about the fact that Fred and George will start at Hogwarts in September, and even if they have Charlie's grown-out-of robes, there will not be enough for both of them, and they will need wands, and two sets of books…

She has no ambitions to be rich, but not having to struggle all the time, and make every Sickle count, would be a luxury.

She wonders if Arthur has remembered the significance of today's date. He usually does, but he said nothing about it when he left for work that morning – but then he hadn't said much at all, because she was so cross about him having to go into work on Easter Saturday and leave her to handle the shopping and the children on her own. He probably thought it was best to keep quiet and get out quick.

She closes her eyes and lets her mind drift. Twenty-three years ago today. She was fifteen and a half, Arthur just sixteen. Both of them younger than Charlie is now. Their first date – if you could call a walk round Hogwarts grounds on a windy Friday night a date. But Arthur had brought chocolate, and given her flowers, and it felt like a date. Twenty three years… It should seem like a long time, but she feels not a lot different from the love-struck fifteen year old who didn't quite believe that Arthur Weasley could be interested in her. How she has got to be old enough to have a grown-up son and another who nearly is, not to mention five other children, she isn't quite sure.

Reality intrudes abruptly on her daydream. The kitchen door bursts open, and the twins tumble in, dragging Ginny between them, and followed by Ron, who spends most of his life trying to keep up with them and never quite managing, and Percy lagging behind in an effort to make it clear that he is not with this unruly bunch of hooligans.

"Are we going yet?" demands Fred – no, it's George – in a voice that makes it sound as if they have been waiting to leave for several hours, rather than barely fifteen minutes since lunch finished.

Molly sighs and pulls herself to her feet. "Yes, yes, we're going," she says. "Where are Bill and Charlie?"

"We're here." The back door opens, and Bill and Charlie come in, laughing at something, the draught from the open door sending their mother's shopping list onto the floor. Charlie picks it up, and frowns as he reads it.

"You know Bill and I can do without Easter eggs, Mum," he tells her quietly as he hands the list back. "And that is definitely a bad idea for the twins' birthday – but they'll love it. D'you want me and Bill to buy it for you? You won't have a clue what you're looking for."

"Would you mind, boys?" Molly asks, smiling up at her two eldest sons. She still finds it disconcerting to have children who are taller than she is, and it won't be long before Percy is as well. "Can you take a twin each in the Floo, you two? Ron can go with Percy, and I'll take Ginny."

"We can go on our own!" Fred proclaims indignantly.

"After the last time you Flooed on your own?" Bill demands, looking very much the elder brother and the Head Boy combined. "I don't think so…"

The shopping trip has gone remarkably well, Molly thinks, as she sips her coffee gratefully in Florean Fortescue's ice cream parlour. (Though she still thinks of it as Giovanni Fortescue's, as it was when she first came here with Arthur. She cannot believe little Florean is old enough to be running it now. He must be over thirty she supposes – yet one more thing to make her feel old.) Bill and Charlie have disappeared to Quality Quidditch Supplies to get the Bludger for Fred and George's birthday; she managed to buy the wool without anyone realising what it was for; and she got the Easter eggs (seven of them, despite what Charlie said earlier) while the children were looking at the owls in Eeylops' and deciding which one they liked best (although Ginny was more taken with the litter of kittens at the back of the shop). Even shoe shopping for Ginny was not as bad as it might have been – she only had to try on eleven pairs before they found one that fitted, which is probably some kind of record. Now the children are eating ice cream, and once Bill and Charlie get back, they can go home. Perhaps she and Arthur might even manage to go out for a drink – a meal would be nicer, of course, but finances will not stretch to it – once the younger children are in bed.

But, of course, something was bound to go wrong. A shopping trip with the whole family in tow could never be so simple…

"Where's Ginny?" Bill asks, as he and Charlie arrive back, Charlie surreptitiously dumping the parcel from the Quidditch supply shop among the others at his mother's feet before the twins notice it.

Molly wakes from her reverie with a jolt, and does a quick head-count. Bill and Charlie standing beside her; Percy sitting quietly at the far end of the table; the twins scraping the last morsels from their ice-cream dishes; Ron scowling at Fred who is obviously kicking him under the table; Ginny… Where is Ginny?

She is on her feet and looking in panic around the ice cream parlour. Ginny was here only a minute ago surely? Where can she have gone? Could someone have taken her? Bill is at the door, looking up and down the crowded street. The other children have just realised something is wrong, and are standing up. Ron has started to cry. She doesn't feel far off it herself. Where has her baby girl gone?

Charlie's arm is round her shoulders, and his voice is reassuring. "Calm down, Mum. She can't be far away."

But Bill is coming back, shaking his head, looking concerned. "Can't see her," he reports. "But it's too crowded to look properly from here."

Florean Fortescue has bustled over to see what is wrong. Charlie explains quickly.

It is remarkable how quickly people organise themselves in an emergency. Within minutes, there is no one in Diagon Alley who does not know that a small girl with red hair and new blue shoes has gone missing. Bill and Charlie are out searching, and have roped in every other Hogwarts student they can find to help. Percy has been taken upstairs by Florean Fortescue to Floo his father at the Ministry. Florean's assistant is plying Molly with strong coffee, and keeping a stern eye on the twins and Ron, who are highly indignant at not being allowed to go out and look for their sister.

Two hours later, what had started as a simple search for a missing child that would take only a few minutes, has a grimmer more purposeful feeling to it. Molly, her face streaked with tears, is still sitting in Fortescue's, talking to an officer from Magical Law Enforcement. This cannot be happening. It just can't. Arthur, white-faced and with his mouth set in a stern line, has joined the other searchers. The family photo from his desk has been taken away so that the part with Ginny laughing on Bill's shoulders can be enlarged for the "Have you seen this child?" posters and flyers which are already being distributed along the Alley and to the parts of Muggle London beyond the Leaky Cauldron. (MLE have arrangements with the Muggle police for occasions such as this.)

Percy, the twins and Ron have been swept off by Andromeda Tonks – "I'll take them, Molly. You don't need to worry about the other children now" – Fred and George unnaturally quiet, Ron staying very close to Percy, as if his brother's proximity will make his sister reappear. Bill and Charlie are out looking. As the time goes on, they find their friends' hands on their shoulders more frequently, voices saying: "We'll find her," more often, as it becomes less and less likely that they will.

There is not a cellar or an attic in Diagon Alley that has not been turned out. Even the deepest passages of Gringotts have been explored, though no one seriously believes a child could have got in there without being noticed. Muggleborn witches and wizards, who can blend easily into the Muggle streets, have gone beyond the Leaky Cauldron to hunt. People are still searching, although they are running out of places to look.

In a dark doorway at the far end of Knockturn Alley, a little girl is huddled, trying to make herself invisible. She has escaped the grabbing hands and the mocking voices – "What's a pretty like you doing here, my love?" – through sheer speed and determination inspired by terror. The ginger kitten that she spotted through the window of Fortescue's and chased along here is long gone, back to its mother. She wants to go back to her mother, but she does not know how to get there. She clings to the hope that Mummy or Daddy or one of her big brothers will find her. They always have before. She holds onto the hope tightly, gripping her hands together as if it is a physical thing. She will not cry.

The searchers are now congregated at the top of Knockturn Alley, but there is an argument going on.

"Only those of you who are of age," a Law Enforcement Officer is insisting to the crowd of Hogwarts students, to a chorus of groans.

"Dad…" Charlie pleads. "She's my sister. Please…"

"Okay, you can come, Charlie," Arthur concedes. He is not about to waste time arguing when his baby girl is out there somewhere. "But you stay with me or Bill. And none of the rest of you who are underage." He glares at the other students. "I'm not being responsible for anyone else losing a child."

There are muffled protests, but the younger students admit defeat, turning back to search again in Diagon Alley in places that have been looked in before, in the hope there is a corner they have somehow missed. Some of the Muggleborns venture through the Leaky Cauldron to the streets beyond, taking others with them. None of them are about to give up and go home. Not while Bill and Charlie's kid sister is still missing.

The others head off down Knockturn Alley, which is unnaturally quiet, the usual sellers and hawkers hiding behind locked doors, knowing that something is going on, worried about being accused of something. The searchers split into twos and threes, some hammering on doors, others bursting into shops they would not normally dream of entering, still others poking about in alcoves and side alleys. Bill and Charlie, wands in hand, make for the far end of the alley, looking in every doorway as they pass, desperate for a sight of Weasley-red hair. They are not talking. For both of them, this whole day has taken on a surreal quality. They cannot do without Ginny. They have to find her. They just have to.

"Bill! Charlie!" A small hurricane with fiery red hair hurtles from a dark doorway and flings herself into Bill's arms. His wand goes flying as he lifts her up and swings her round, laughing and crying at the same time. Charlie joins in the hug, and then retrieves Bill's wand from the gutter, using it to send gold sparks high into the air – the agreed signal for "Found!" and hang the laws about underage magic out of school. (He used Bill's wand – if anyone asks, they will say it was Bill who did it.)

Their father is there in less time than seems possible, pulling Ginny from Bill's arms and holding her close. Knockturn Alley has never known so much laughter and sheer noise. Ginny is borne back to Fortescue's in triumph in her father's arms, Bill and Charlie on either side, hanging onto any bit of her they can reach, not about to let their sister go now that they have her back.

Molly, predictably, dissolves in tears at the sight of her missing daughter, and has to be dosed by Poppy Pomfrey, who has appeared from somewhere, with strong coffee and firewhisky. In dribs and drabs, the searchers make their way to the ice-cream parlour, and Florean and his assistant are rushed off their feet providing coffee and ice cream – "On the house, of course!" Florean proclaims expansively – for everyone. Someone Floos the Tonks' house, and the other Weasley children return, the twins and Ron – in perfect agreement for once – executing a kind of triumphant war-dance around their parents and Ginny, and Percy disgracing himself by bursting into such a storm of tears that he has to be taken outside by Bill until he calms down.

The impromptu party goes on for a long time, long after the shops have closed and the gaslights are lit. Ginny, exhausted by her adventure, falls asleep across her parents' laps, her hand holding her mother's even in sleep. Molly leans gratefully against Arthur, looking down at Ginny's chubby fingers encircling her own.

They may not be rich, but she has everything she needs.